Digital situation indicator

ABSTRACT

The present invention relates to a digital situation indicator, especially a personal monitoring and alarm system. The digital situation indicator according to the invention consist of three parts: sensor module (SM) for monitoring desired data, heads-up display module (HUD) mounted in a facemask (F) or helmet of the operating person, and incident commander module (ICM) at a distance from the operating person. The digital situation indicator can be used to monitor for example firefighter&#39;s heat stress, amperage in a welding machine or warfighter&#39;s dosage of chemical warfare agents.

FIELD OF THE INVENTION

[0001] The present invention relates to a digital situation indicator, especially a personal monitoring and alarm system as defined in the preamble of claim 1.

BACKGROUND OF THE INVENTION

[0002] When entering a burning building, firefighters wear breathing apparatus consisting of an air tank, regulator, facemask and pressure gage. Typically, firefighters work in dense smoke, where the visibility may be only a few inches.

[0003] Firefighters carry a personal alert safety system (PASS) device, which activates an audible alarm, if they stop moving. The PASS device has a “Pre-Alert” stage, which allows the firefighter a pre-specified number of seconds to move or to shake the PASS device, before the alarm is activated. In addition to the PASS device, firefighters need to know certain information about their constantly changing situation in order to safely and efficiently perform their work.

[0004] At minimum, firefighters need to know at all times, how much air is remaining in their tank. The pressure of the air tank will only tell part of the story. Two firefighters with identical pressure gage readings may each have a different number of minutes of air time remaining, depending on their respective rates of air consumption. The rate of air consumption varies from firefighter to firefighter according to size, physical conditioning, and metabolic rate. The rate of air consumption also can change from minute to minute for an individual firefighter depending on the intensity of the physical work being performed, stress, and other factors. Therefore, the firefighter needs to know both the air pressure and its equivalent in number, of minutes remaining, at any given time.

[0005] For safety reasons, the firefighter also needs to know the ambient temperature, its time-dependent effect on his or her cumulative heat stress level, and whether flashover conditions are impending. Before opening a door inside a burning building, the firefighter needs to know whether there is a raging fire on the other side. During so-called “mop-up” operations after the fire has been extinguished, firefighters typically have to use axes to inspect inside walls, to ensure that no hidden fires exist.

[0006] Firefighters wear thick gloves, carry axes and water hoses, and need their hands free to be able to perform their work. Gages that attach to the air hose and hang from the firefighter's side are inconvenient to continuously pick-up and, in dense smoke, are almost impossible to read. When brought up to the facemask, the gage is too close for the firefighter's eyes to focus. For this reason, an elementary display system has recently been invented, consisting of a series of Light Emitting Diodes (LEDs) mounted inside the facemask. The drawback to this approach is that the LEDs provide much less information than gages provide.

[0007] A helmet-mounted display system such as those used by military jet fighter pilots, which projects data onto the visor of the helmet, would offer firefighters a possible solution. However, the cost of a single helmet could absorb an annual budget. The cost to equip all firefighters worldwide would be staggering.

[0008] Another occupational group working with impaired visibility are welders. When welding certain types of material, such as stainless steel or aluminum, certain amperage settings for the welds may be specificated in the manufacturing drawings, and it is necessary to the welder from time to time to check the amperage gage. In many cases the welder has to work severeral meters away from the welding machine, and he has to flip up his helmet and walk back to read the gage. If the welder is working on a ladder or a scaffold, he has to climb down or ask someone else to read the amperage.

[0009] Remote controls for setting the amperage are available, and to save time welders sometimes try to set the amperage based on experience. If the amperage is set incorrectly with this method, the result can be a weld that is out of the specification or a rejected part.

[0010] Also warfighters suffer from impaired visibility when chemical warfare agents (CWA) are present and they have to wear gas masks and protective clothing Sometimes warfighters have to work in even more impaired visibility conditions, for example after a bombardment the battlefield is covered with smoke.

[0011] Warfighters carry CWA detection instruments, which indicate the presence of any chemical warfare agent. When the CWA detection instrument detects the presence of CWA, it activates an audible alarm, and warfighters put on their gas masks and protective clothing. The CWA detection instrument continues to monitor the level of present CWA, and informs the warfighter when it is safe to take of the gas mask.

[0012] The CWA detection instrument also continuously measures the concentration of chemical warfare agents in the surrounding. To be all the time aware of the current concetration, warfighters need to look at the instrument frequently. Current instruments are handheld and warfighters need pick them up to read them, same time forcing him to release grip from his tools or weapon.

[0013] Displays of these current handheld instruments are small and they are not protected from mud and dirt. Also dense smoke can impaire the readability of the instrument. To improve the readability of these current CWA detection instruments their displays are often illuminated. This inturn can reveal the warfighter to the enemy. One detection instrument is also needed for each warfighter, which adds weight to the warfighter's gear and increases costs.

[0014] The incident commander (IC) is in charge of all firefighters at the scene of the fire. Each firefighter gives the IC a personal accountability tag (PAT) upon arrival at the scene. The IC keeps track of the firefighters by the use of a unit identification pad (UIP) and a large marker board. The drawback is that once the firefighters are inside the fire, the IC has no method of knowing how much air each firefighter has left, what temperature the firefighters are operating in, what is their heat stress level or PASS device status.

[0015] The commanding officer (CO) of a certain part of the battlefield is tracking the overall CWA concentration of that area. Warfighters report their instrument readings to the CO either using a radio or a courier. The drawback is that the CO can not keep track of the CWA concentration or the dosage of an individual warfighter in realtime.

[0016] Firefighters, welders and warfighters are just examples for possible users of digital situation indicator of the invention. This kind of indicators can be utilised in many fields where personal monitoring and alarming are essential.

SUMMARY OF THE INVENTION

[0017] A primary object of the present invention is to provide a digital situation indicator, especially a personal monitoring and alarm system that will overcome the shortcomings of the prior art devices. Another object of the invention is to provide a new digital situation indicator.

[0018] The invention is characterized by the features defined in claim 1. The dependent claims describe preferred embodiments of the invention.

[0019] The situation indicator SI of the invention offers a digital heads-up display HUD solution with a multitude of new features. The SI offers a truly digital, very easily legible HUD, at a cost no more expensive than the existing technology.

[0020] The SI system has three separate units:

[0021] Sensor Module SM for monitoring desired data,

[0022] Heads-Up Display HUD mounted in the facemask F of the operating person, and

[0023] Incident Commander Module ICM at a distance from the operating person.

[0024] The sensor module may contain a pressure sensor, ambient temperature sensor, infrared (IR) temperature sensor, an “SOS” Button and an integrated PASS device. A microprocessor analyses the sensor data and computes air time remaining in minutes, heat stress level, and impending flashover danger. The sensor module transmits sensor and computed data to both the HUT and the ICM. The communication between the parts is preferably wireless such as radio frequency (RF) communication.

[0025] The sensor module may also contain a amperage sensor. The sensor module transmits sensor and computed data to the HUD using preferably wireless communication, such as RF communication.

[0026] The sensor module may also contain a chemical warfare agent sensor. A microprocessor analyses the sensor data and computes CWA concentration in the surrounding and the dosage of an individual warfighter.

[0027] The heads-up display incorporates a miniature, transflective LCD display unit with electro-luminescent panel backlighting, and optical enhancement means consisting of an achromatic doublet lens, optimized to correct for on-axis spherical and chromatic aberrations. The optics is designed for extra long eye relief, and the HUD is positioned in the facemask so that it does not restrict the firefighter's forward field of view.

[0028] With the SI system, before opening a door inside a burning building, the firefighter can point the IR sensor with a laser beam at the door, press the IR sensor button and read the temperature of the door on the HUD. During “mop-up” operations after the fire has been extinguished, the firefighter can scan the walls with the IR sensor to ensure that no hidden fires exist.

[0029] The incident commander module consists of a self contained, portable, one-piece computer module, with backlit LCD display, touch screen or flex-membrane keypad, and RF transceiver. The ICM receives data transmissions from the sensor module. The ICM can also transmit text messages to the fire- or warfighter. Once the firefighter is inside the fire, the ICM tracks each firefighter's situation, including elapsed time in the fire, air pressure, air time remaining in minutes, ambient temperature in the fire, heat stress level and PASS device status. It may also track each warfighter's situation, including time under exposure to CWA and dosage of CWA.

[0030] The advantages of the invention are, among the other things, the following:

[0031] the SI system is a compact and versatile system for a user and,

[0032] effective communication between different parts of the SI system,

[0033] a user has clear and concise information for use,

[0034] it is possible to follow a user with his/her sensor module inside the fire or equivalent work and communicate, if necessary.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] A preferred embodiments of the invention are presented in the following with reference to the attached drawing in which:

[0036]FIG. 1 shows a schematic block diagram of the sensor module according to the first embodiment of the invention,

[0037]FIG. 2 shows a schematic block diagram of the sensor module according to another embodiment of the invention,

[0038]FIG. 3 shows a schematic block diagram of the sensor module according to another embodiment of the invention,

[0039]FIG. 4 shows a block diagram of the heads-up display,

[0040]FIG. 5 shows a block diagram of the incident commander module,

[0041]FIG. 6 shows a perspective view of the sensor module attached to an air tank,

[0042]FIG. 7 shows more closely the sensor module,

[0043]FIG. 8 shows a mask with the heads-up display,

[0044]FIG. 9 shows a welders helmet with the heads-up display,

[0045]FIG. 10 shows more closely the heads-up display as perspective view,

[0046]FIG. 11 shows examples of information which can be presented in the heads-up display according to the first embodiment of the invention,

[0047]FIG. 12 show example of information which can be presented in the heads-up display according to another embodiment of the invention,

[0048]FIG. 13 shows examples of information which can be presented in the heads-up display according to another embodiment of the invention,

[0049]FIG. 14 shows a perspective view of the incident commander module,

[0050]FIG. 15 shows a flow diagram of the Flashover Warning Alarm software according to the first embodiment of the invention,

[0051]FIG. 16 shows a flow diagram of the Cumulative Heat Stress Level calculating software according to the first embodiment of the invention, and

[0052]FIGS. 17a and 17 b show a flow diagram of the Motion Sensor software according to the first embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0053] Digital situation indicator SI for firefighters—system highlights:

[0054] Pressure sensor—senses pressure remaining in the air tank of the firefighter;

[0055] Computes minutes of air time remaining at firefighter's current consumption rate;

[0056] Ambient temperature sensor—senses ambient temperature;

[0057] Flashover warning alarm—warns of impending flashover danger;

[0058] Computes heat stress level, in “degree-minutes”;

[0059] Integrated Personal Alert Safety System PASS device;

[0060] Infrared (IR) sensor, activated by the push of a button—detects fire and/or high temperatures behind closed doors and inside walls;

[0061] Visible light LASER to show where IR sensor is pointed;

[0062] “SOS” button—transmits emergency signal to ICM and activates audible alarm;

[0063] Service records datalogger—records sensor module service and maintenance information in non-volatile memory.

[0064] The sensor module SM in accordance with one embodiment of the invention, as shown in FIG. 1, has the following parts and features:

[0065] Sensor module SM scans all sensor readings and transmits updated sensor data to both HUD and ICM, preferably every 3 seconds;

[0066] Pressure sensor 1—senses air pressure in the air tank 2 (FIG. 6);

[0067] Control unit, such as microprocessor 3, tracks firefighter's rate of air consumption, then computes air time remaining in minutes at current consumption rate;

[0068] Ambient temperature sensor 4—senses ambient temperature;

[0069] Flashover warning alarm—software analyses sensor data and detects, when ambient conditions are appropriate for impending flashover. Microprocessor 3 transmits flashover warning to both HUD and ICM, and/or activates audible alarm 5.

[0070] The operation of the flashover warning software is described in the flow chart of the FIG. 15. First the pre-specified alarm limits and the ambient temperature T_(A) are read and the real time clock is started. Then the ambient temperature is stored in to the memory as a function of time and the rate of increase of ambient temperature is calculated. After this the ambient temperature is compared to the pre-specified alarm limit and if the ambient temperature is lower than the limit, the program returns to the beginning.

[0071] If the ambient temperature is higher than pre-specified alarm limit, the rate of increase of ambient temperature is compared to the pre-specified alarm limit. If the rate of increase of ambient temperature is lower than the limit, the program returns to the beginning. If the rate of increase of ambient temperature is higher than the pre-specified alarm limit, a flashover warning is displayed in the HUD. A flashover warning is also transmitted to the incident commander module;

[0072] Microprocessor 3 records firefighter's duration in high temperatures and computes cumulative heat stress level, in “degree-minutes”. Software includes computation for rehabilitation (Rehab) time as well as multiple tank 2 usage. The operation of the cumulative heat stress level program is described in the flow chart of the FIG. 16. First the pre-specified alarm limits and the ambient temperature T_(A) are read and the real time clock is started. Then the ambient temperature is stored in to the memory as a function of time and the cumulative heat stress level is calculated. After this the cumulative heat stress level is displayed in the HUD.

[0073] If the cumulative heat stress level is higher than the pre-specified alarm limit, a heat stress warning alarm is activated and an alarm message is transmitted to the incident commander module. If the cumulative heat stress level is lower than the pre-specified alarm limit program returns to the beginning;

[0074] Integrated personal alert safety system “PASS” device, including:

[0075] Motion sensor 6 to detect absence of motion by firefighter;

[0076] Vibrator 7 and/or audible alarm 5 to alert firefighter of “Pre-Alert” condition;

[0077] Transmitter 8 to transmit “Pre-Alert” condition data to HUD and ICM;

[0078] Audible alarm 5, activated after a pre-specified number of seconds of absence of motion.

[0079] The operation of the motion sensor program is described in the flow chart of the FIGS. 17a and 17 b. First the pre-specified alarm limits and the motion sensor are read and the real time clock is started. Then the motion is stored in to the memory as a function of time. If the motion stops, time period of zero motion is calculated.

[0080] If the time period of zero motion is shorter than the pre-specified limit, program returns to the beginning. Otherwise a countdown timer and a vibrator alarm are activated. Simultaneously zero motion warning and countdown timer data is displayed in the HUD. A zero motion warning is also transmitted to the incident commander module.

[0081] After this the motion sensor is read again. If motion is detected, the countdown timer is reset and a all clear message is transmitted to the incident commander module, and the program returns to the beginning. Otherwise the countdown timer is checked, and if there is still time left, motion sensor is read again. If countdown timer has reached zero, an audible alarm is activated and an alarm message is transmitted to the incident commander module.

[0082] Infrared (IR) sensor 9, activated by the push of a button 10 (FIG. 9)—detects infrared radiation emitted from closed doors and walls (and therefore fire and/or high temperatures behind closed doors and inside walls);

[0083] Visible wavelength coaxial LASER 11 (FIG. 7) to show with its beam 11 a where IR-sensor 9 is pointed;

[0084] SOS-button 20—activates audible alarm and transmits signal to ICM;

[0085] Radio frequency (RF) receiver 12—receives text messages from ICM and forwards them to HUD;

[0086] Service records datalogger—records sensor module service and maintenance information in non-volatile memory 13;

[0087] “Automatic On” feature—activated upon opening of air tank regulator valve;

[0088] Optional button(s) 14 to allow firefighter to input his/her identification code;

[0089] Optional “Black Box” datalogger—records all sensor data during fire, with automatic “Time Stamping”,

[0090] Optional emergency locator transmitter (ELT), activated by PASS device or SOS-button.

[0091] The sensor module SM is attached to the pressure gage hose 15 of the air tank 2 as shown in FIG. 4. The sensor module SM has a connector 16 to the pressure hose 15, a housing 17 for the electronic circuitry (shown in FIG. 1) of the sensor module SM, RF antenna 18, IR-sensor and ambient temperature sensor in their housing 19, a waterproof switch 10 for IR-sensor 9 (FIG. 1), a laser 11 and SOS-button 20.

[0092] Digital situation indicator SI for welders—system highlights:

[0093] Amperage sensor—senses the amperage of a welding machine;

[0094] The sensor module SM in accordance with another embodiment of the invention, as shown in FIG. 2, has the following parts and features:

[0095] Sensor module SM scans all sensor readings and transmits updated sensor data to HUD, preferably every 3 seconds;

[0096] Amperage sensor 1—senses amperage of a welding machine;

[0097] Service records datalogger—records sensor module service and maintenance information in non-volatile memory 13;

[0098] “Automatic On” feature—activated upon turning the welding machine on;

[0099] Optional “Black Box” datalogger—records all sensor data during welding, with automatic “Time Stamping,”,

[0100] The sensor module SM is attached to the welding machine. The sensor module SM has a connector to the amperage gage, a housing for the electronic circuitry (shown in FIG. 2) of the sensor module SM and RF antenna.

[0101] Digital situation indicator SI for warfighters—system highlights:

[0102] Chemical warfare agent sensor—senses the amount of CWA in the surroundings.

[0103] Computes warfighter's total dosage of CWA;

[0104] Computes the remaining operating time at current CWA consentration;

[0105] “SOS” button—transmits emergency signal to ICM and activates audible alarm;

[0106] Service records datalogger—records sensor module service and maintenance information in non-volatile memory.

[0107] The sensor module SM in accordance with another embodiment of the invention, . shown in FIG. 3, has the following parts and features:

[0108] Sensor module SM scans all sensor readings and transmits updated sensor data to both HUD and ICM, preferably every 3 seconds;

[0109] Chemical warfare agent sensor 32—senses the amount of CWA in the surroundings;

[0110] Control unit, such as microprocessor 3, tracks warfighter's CWA dosage, then computes remaining operating time with current CWA consentration;

[0111] SOS-button—activates audible alarm and transmits signal to ICM;

[0112] Radio frequency (RF) receiver 12—receives text messages from ICM and forwards them to HUD;

[0113] Service records datalogger—records sensor module service and maintenance information in non-volatile memory 13;

[0114] “Automatic On” feature—activated upon turning on of the CWA sensor;

[0115] Optional button(s) to allow warfighter to input his/her identification code;

[0116] Optional “Black Box” datalogger—records all sensor data during presence of CWA, with automatic “Time Stamping”,

[0117] Optional emergency locator transmitter (ELT), activated by SOS-button.

[0118] The sensor module SM is attached to the chemical warfare agent sensor. The sensor module SM has a housings for the electronic circuitry (shown in FIG. 3) of the sensor module SM, RF antenna housing and SOS-button.

[0119] The heads-up display HUD is an optielectric, night-readable display which is mounted in a facemask F of the firefighter or warfighter, or to the helmet of the welder as shown in FIG. 8 and FIG. 9. The heads-up display module HUD, as shown in FIG. 4, has the following parts and features:

[0120] Control unit such as a microprocessor 24, display 21, preferably electro-luminescent backlit 22, miniature digital LCD display or equivalent;

[0121] Use of optical enhancement to create an easily legible digital display, which can be located inside the facemask as shown in FIG. 8 as an example—specifically, an achromatic doublet lens 22, optimized to correct for on-axis spherical and chromatic aberrations, with extra long eye relief, positioned so as not to restrict the firefighter's forward field of view;

[0122] RF receiver 25 for receiving data from the sensor module SM;

[0123] Housing 23 into which the display 21 and the lens 22 are fixed;

[0124] The display 21 in accordance with one embodiment of the invention is arranged to function as following indicators:

[0125] Pressure indicator—indicates pressure remaining in air tank;

[0126] Time remaining indicator—indicates air time remaining in minutes, at current consumption rate;

[0127] Ambient temperature indicator—displays ambient temperatures (compare FIG. 11):

[0128] Heat stress indicator—displays firefighter's cumulative heat stress level;

[0129] Flashover warning indicator—alerts firefighter of impending flashover dancer;

[0130] Infrared temperature indicator—displays infrared temperature of object that IR-sensor is pointed towards, whenever IR-sensor button is pushed (compare FIG. 8);

[0131] PASS device condition indicator—alerts firefighter of “Pre-Alert” PASS condition;

[0132] The display in accordance with another embodiment of the invention is arranged to function as following indicators:

[0133] amperage indicator—indicates pressure remaining in air tank;

[0134] The display in accordance with another embodiment of the invention is arranged to function as following indicators:

[0135] CWA indicator—indicates consentration of CWA in the surrounding and changes the color of the display depending the situation;

[0136] Time remaining indicator—indicates remaining operating time in minutes at current CWA consentration;

[0137] Furthermore, the heads-up display module has:

[0138] “Sleep mode”—provides “Automatic On” feature and prolonged battery life;

[0139] Optional two-way RF voice communication between firefighter and incident commander.

[0140] The incident commander module ICM of one embodiment of the present invention provides the incident commander, who is commanding the operation, with real-time sensors data on all firefighters in the interior of the building or equivalent. The incident commander module ICM as shown in FIG. 5 and FIG. 14, has the following parts and features:

[0141] Control unit such as a microprocessor 26;

[0142] RF Transceiver 27, which receives continuous RF sensor data transmissions from up to 128 firefighters, specifically from the firefighter's sensor modules SM;

[0143] Display 28 such as backlit LCD display, indicates the following for each firefighter:

[0144] Elapsed time inside the fire;

[0145] Pressure in air tank;

[0146] Air time remaining in minute;

[0147] Ambient temperature reading;

[0148] IR sensor reading;

[0149] Heat stress level;

[0150] Flashover warming;

[0151] PASS device status, including “Pre-Alert” condition;

[0152] Receives “SOS” transmission and identifies firefighter in trouble;

[0153] Transmits text messages by means of the RF transceiver 27 to any selected firefighter or to all firefighters;

[0154] Illuminates “Service” icons, to indicate when upcoming service is due for ICM, HUDs or sensor modules;

[0155] “Black Box” datalogger built into ICM;

[0156] records each firefighter's situation in real-time, as it occurs;

[0157] records any firefighter's “SOS” transmission in real-time, as it occurs;

[0158] records the ICM's text messages in real-time, as they occur;

[0159] records all service and maintenance records on each device;

[0160] automatically adds “Time/Date Stamp” to all records.

[0161] Field programming capacity—enables ICM to download identification codes and other information to non-volatile memory in sensor modules and HUDs;

[0162] Optional two-way RF voice communication between firefighter and incident commander.

[0163] The incident commander module ICM of another embodiment of the present invention provides the commanding officer, who is commanding certain part of the battlefield, with real-time sensors data on all warfighters in the area. The incident commander module ICM as shown in FIG. 5 and FIG. 14, has the following parts and features:

[0164] Control unit such as a microprocessor 26;

[0165] RF Transceiver 27, which receives continuous RF sensor data transmissions from up to 128 warfighters, specifically from the warfighter's sensor modules SM;

[0166] Display 28 such as backlit LCD display, indicates the following for each firefighter:

[0167] Elapsed time under CWA;

[0168] CWA concentration in the surrounding;

[0169] current dosage of CWA;

[0170] remaining operating time in minutes;

[0171] Receives “SOS” transmission and identifies warfighter in trouble;

[0172] Transmits text messages by means of the RF transceiver 27 to any selected warfighter or to all warfighters;

[0173] Illuminates “Service” icons, to indicate when upcoming service is due for ICM, HUDs or sensor modules;

[0174] “Black Box” datalogger built into ICM;

[0175] records each warfighter's situation in real-time, as it occurs;

[0176] records any warfighter's “SOS” transmission in real-time, as it occurs;

[0177] records the ICM's text messages in real-time, as they occur;

[0178] records all service and maintenance records on each device;

[0179] automatically adds “Time/Date Stamp” to all records.

[0180] Field programming capacity—enables ICM to download identification codes and other information to non-volatile memory in sensor modules and HUDs;

[0181] Optional two-way RF voice communication between warfighter and incident commander. 

1. A digital situation indicator, especially a personal monitoring and/or alarm system, characterized in that the situation indicator (SI) has three separate units: a sensor module (SM) for an operating person having a plurality of sensors (1, 4, 6, 9; 32) for monitoring conditions in connection with the operating person and a control unit (3) for analysing the data collected; a heads-up display (HUD) module mounted in a facemask (F) or helmet of the operating person for displaying collected and analysed data; an incident commander module (ICM) at a distance from the operating person for providing an incident commander with real-time sensors data on all operating persons in the operating area; and communication means (8, 12, 27) in said modules (SM, HUD, ICM) for sending and receiving data between the sensor module (SM) and the heads-up display (HUD) module of the operating person and further between the sensor module and the incident commander module (ICM).
 2. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, characterized in that the situation indicator has three separate units: a sensor module (SM) including plurality of sensors (1, 4) for monitoring conditions in connection with a firefighter such as an ambient temperature sensor, and a sensor for the pressure of the air tank; and control unit such as a microcomputer (3) for analysing the data collected; which sensor module (SM) has further: flashover warning alarm for analysing sensor data and detecting, when ambient conditions are appropriate for impending flashover; means for computing cumulative heat stress level and heat stress warning alarm; personal alert safety system (PASS) having motion sensor (6) and alarm (5; 7); SOS button (20); and radio frequency transceiver (8, 12) for transmitting sensor data, computed data and alarms to a heads-up display (HUD) module and/or an incident commander module (ICM) and receiving messages from the incident commander module (ICM); a heads-up display (HUD) module, which is positioned in a facemask or a helmet of the firefighter for displaying collected and analysed data, and an incident commander module (ICM) at a distance from the firefighter for providing an incident commander with real-time sensors data on all firefighters in the area, which incident commander module (ICM) has: control unit such as a microprocessor (26); radio frequency transceiver (27) for receiving sensor data transmissions and SOS transmissions from a plurality of firefighters, especially from their sensor modules (SM), and for transmitting messages to any selected firefighter or to all firefighters; and display (28) for indicating information from the firefighters;
 3. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to claim 2, characterized in that the sensor module includes an infrared temperature sensor (9) for detecting fire and/or high temperature behind closed doors and inside walls and a visible light laser ( 11) to show with its beam where the sensor (9) is pointed.
 4. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to claim 3, characterized in that the infrared temperature sensor (9) has a switch (10) such as a button for activating the sensor.
 5. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of claims 2-4, characterized in that the sensor module (SM) has an emergency locator transmitter (ELT) activated by personal alert safety system (PASS) or SOS button (20).
 6. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of claims 2-5, characterized in that the sensor module (SM) is attached to the pressure gage hose (15) of the air tank (2).
 7. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of claims 3-6, characterized in that the sensor module has two housings (17, 19) connected to each other, where the first housing (17) for the electronic circuitry and the second housing (19) for the coaxially arranged infrared temperature sensor (9) and laser (11) and further for the IR sensor activating switch (10) and SOS-button (20).
 8. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of claims 2-7, characterized in that the heads-up display (HUD) module has a control unit such as a microprocessor (24), a display, preferably electro-luminescent backlit (22) miniature, digital liquid crystal display (21), and optical enhancement means, specifically an achromatic doublet lens (22), optimised to correct for on-axis spherical and chromatic aberrations, which display (21) is positioned in a facemask or a helmet.
 9. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to claim 8, characterized in that the display (21) is arranged to function as following indicators: pressure indicator for indicating pressure remaining in the air tank; time remaining indicator for indicating air remaining in minutes at current consumption rate; ambient temperature indicator for displaying ambient temperatures; heat stress indicator for displaying firefighter's cumulative heat stress level; flashover warning indicator for alerting the firefighter of impending flashover danger; personal alert safety system (PASS) device condition indicator for alerting the firefighter of pre-alert condition; and infrared temperature indicator for displaying infrared temperature of the object that the infrared temperature sensor (9) is pointed towards.
 10. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of preceding claims 2-9, characterized in that the heads-up display (HUD) module has a two-way radio frequency voice communication between any of the firefighters and an incident commander by means of the incident commander module (ICM).
 11. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of preceding claims 2-10, characterized in that the incident commander module (ICM) is arranged to transmit text messages by means of the transceiver (27) to any selected firefighter or to all the firefighters.
 12. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of preceding claims 2-11, characterized in that the display (28) of incident commander module (ICM) is arranged to indicate the following information for each firefighter: elapsed time inside the fire; pressure in the air tank and air remaining in minute; ambient temperature reading; heat stress level; flashover warning; status of the personal alert safety system (PASS) device; and reading of the infrared temperature sensor (9).
 13. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of preceding claims 2-12, characterized in that the incident commander module (ICM) has a datalogger which is arranged to record the following information each firefighter's situation in real-time, as it occurs; any firefighter's SOS transmission on real-time, as it occurs; all service and maintenance records on each device; and automatically to add time/date stamp to all records.
 14. A digital situation indicator, especially a personal monitoring and alarm system for firefighters, according to any of preceding claims 2-13, characterized in that the incident commander module (ICM) has a field programming capacity, which enables to dawn load identification codes and other information from the incident commander module (ICM) to the sensor module (SM) and the heads-up display (HUD) module of the firefighter.
 15. A digital situation indicator, especially a personal monitoring and alarm system for war fighters, characterized in that the situation indicator has three separate units: a sensor module (SM) including a plurality of sensors (1, 4) for monitoring conditions in connection with a war fighter, and a control unit such as a microcomputer (3) for analysing the data collected; which sensor module has further: chemical warfare agent sensor (32) for sensing the amount of the agent in the surroundings; means for tracking war fighter's chemical warfare agent dosage; means for computing remaining operating time with current chemical warfare agent concentration; SOS button (20); and radio frequency transceiver (8, 12) for transmitting sensor data, computed data and alarms to the heads-up display (HUD) module and/or an incident commander module (ICM) and receiving messages from the incident commander module (ICM). a heads-up display (HUD) module, which is positioned in a facemask or a helmet of the war fighter for displaying collected and analysed data, and an incident commander module (ICM) at a distance from the war fighter for providing an a commanding officer with real-time sensors data on all war fighters in the area, which incident commander module (ICM) has: control unit such as a microprocessor (26); radio frequency transceiver (27) for receiving sensor data transmissions and SOS transmissions from a plurality of war fighters, especially from their sensor modules (SM), and for transmitting messages to any selected war fighter or to all war fighters; and display (28) for indicating information from the war fighters.
 16. A digital situation indicator, especially a personal monitoring and alarm system for war fighters, according to claim 15, characterized in that the sensor module (SM) has an emergency locator transmitter (ELT) activated by SOS button.
 17. A digital situation indicator, especially a personal monitoring and alarm system for war fighters, according to claim 15 or 16, characterized in that heads-up display (HUD) module has a display (21), which is arranged to function as following indicators: chemical warfare agent indicator for indicating concentration of chemical warfare agent in the surroundings and changing the colour of the display depending on the situation; and time remaining indicator for indicating operating time in minutes at current chemical warfare agent concentration.
 18. A digital situation indicator, especially a personal monitoring and alarm system for war fighters, according to any of claims 15-17, characterized in that the display (28) of incident commander module (ICM) is arranged to indicate the following information for each war fighter: elapsed time under chemical warfare agent; chemical warfare agent concentration in the surroundings; current dosage of chemical warfare agent; and remaining operating time in minutes.
 19. A digital situation indicator, especially a personal monitoring and alarm system for war fighters, according to any of claims 15-18, characterized in that the incident commander module (ICM) is arranged to transmit text messages by means of the radio frequency transceiver (27) to any selected war fighter or to all war fighters.
 20. A digital situation indicator, especially a personal monitoring and alarm system for war fighters, according to any of claims 15-19, characterized in that the incident commander module (ICM) has a datalogger, whish is arranged to record each war fighter's situation in real-time; any war fighter's SOS transmission in real-time, as it occurs; all service and maintenance records on each sensor module; and automatically to add time/date stamp to all records.
 21. A digital situation indicator for welders, characterized in that the indicator has a sensor module (SM) and a heads-up display (HUD) module, where the sensor module (SM) is attached to a welding machine including an amperage sensor (31) for monitoring amperage of the welding machine, control unit such as a microcomputer (3) for analysing the data collected; and radio frequency transceiver (8, 12 FIG. 2) for transmitting updated sensor data to the heads-up display (HUD) module; and the heads-up display (HUD) module is positioned in a facemask or a helmet of the welder for displaying in its display (21) collected and analysed data.
 22. A digital situation indicator for welders according to claim 21, characterized in that the sensor module (SM) has a datalogger, whish is arranged to record: all sensor data during welding; sensor module service and maintenance information in a memory (13); and automatically to add time/date stamp to all records.
 23. A digital situation indicator for welders according to claim 21 or 22, characterized in that the display (21) is arranged to function as an amperage indicator for indicating the amperage of the welding machine. 